1. Field of the Invention
The present invention relates to a xerographic apparatus such as a copier, laser printer, etc., and more particularly to a transferring device for transferring an image formed on a photoconductor built in such an apparatus as mentioned above.
2. Description of the Related Art
The configuration of a conventional corona charger (transferring device) and a method of mounting it in the body of a xerographic apparatus will now be explained with reference to FIG. 7 through FIG. 10. According to a first example of the prior art (FIG. 7) disclosed in Japanese Patent Application Disclosure HEI 4-230777, a corona charger type transferring device 100 is equipped with a charger wire 83 in a corona case 82 on the side of which are provided a holder 90 at the front of the device (the front of the body of the xerographic apparatus, that is, the end of the body in the direction opposite to that indicated by the arrow A in FIG. 7), and a positioning shaft 87 at the rear of the device (the rear of the body of the xerographic apparatus, that is, the end of the body in the direction of the arrow A in FIG. 7), with a plate spring member 88 and a guide member 89 provided at the bottom of the corona case 82. Referring to FIG. 8, the aforementioned guide member 89 is inserted into a base plate guide rail 91 at the side of the body (base plate side) of the xerographic apparatus, for mounting the corona charger type transferring device 100. Here, the positioning of the corona charger type transferring device 100 is accomplished by proper insertion of the positioning shall 87 in a recess portion of the body. Since the aforementioned method utilizes holding power of the plate spring member 88, no additional means (vis or the like) is provided for securing the corona charger type transferring device 100 to the body of the xerographic apparatus.
A second example of the prior art shown in FIG. 9 is a method of securing a holder section 85 of a corona charger type transferring device 100 to a base plate 81 with a vis 86. According to a third example of the prior art shown in FIG. 10, a wire holder 85 for securing a charger wire 83 is formed integrally with a base plate 81, with a corona case 82 secured directly to the base plate 81 with a vis 86. The charger wire 83 is also secured directly to the base plate 81 with a vis 84.
With the first example of the prior art, although the user may mount and demount the corona charger type transferring device, in cases where the user has forgotten to remount the corona charger type transferring device which has been removed for some reason, or has failed to properly insert it in the guide rail, failure of image formation, damage to the corona charger type transferring device and other troubles occur. Further, in cases where the body of the xerographic apparatus is designed to be capable of managing such troubles, it becomes necessary to provide the body with special additional parts or an improved insertion guide as countermeasures, and such provision results in a great increase in cost.
On the other hand, according to the second embodiment or the prior art, in cases where the corona charger type transferring device is secured with a screw so that only service technicians may remove it, it becomes necessary to expend much time and effort to remove the vis and a driver must also be used inside the body of the xerographic apparatus if the screw is located inside the body; a series of these procedures requires advance special training and use of an extra-short driver (a special-purpose tool), and thus is a time-consuming job.
According to the third example of the prior art, replacement of the inner wire electrodes is difficult and complicated work even for service technicians.